Water armed air safetied detonator

ABSTRACT

A water-armed, air-safe fuze for hand grenades, bombs, mines and torpedoes which permits initiation of the main charge only when the device is underwater. A floodable chamber having flooding holes open to the environment is intermediate an explosively driven piston and a percussion primer. When water fills the floodable chamber, sufficient forces will be transmitted from the driver piston to an intermediate firing pin which will be ejected toward the percussion primer to initiate the main charge in the ordnance. When air fills the chamber, insufficient forces will be transmitted and the device will be safetied.

United States Patent 1191 Montesi Oct. 16, 1973 [54] WATER-ARMED AIR SAFETIED 3,147,667 9/1964 Vaughn 89/1 B DETONATOR 3,204,559 9/l965 Matthew....

3,618,522 11/1971 Henderson .1 l02/64 [75] Inventor: Louis J. Montesi, Colesville, Md.

73 Assignee: The United States of America as Primary Examinerverlin Pendegrass represented by the Secretary of the Attorney-"R sciascia et Navy, Washington, DC. [22] Filed: Apr. 11, 1972 [57] ABSTRACT A water-armed, alt-safe fuze for hand grenades, pp No 242,990 bombs, mines and torpedoes which permits initiation of the main charge only when the device is underwa- 52 US. 01. 102/16, 102/64 A fleetiabie chamber having flooding holes 0Pen 51 Int. Cl. F42b 27/08, F420 15/02 to the environment is intermediate an explosively 58 Field Of Search 102/10, 16, 64, 65, driven piston and a Percussion P when Water 102/654 81; 89/1 B fills the floodable chamber, sufficient forces will be transmitted from the driver piston to an intermediate [56] References Cited firing pin which will be ejectecli1 toward tllile perfussion primer to initiate the main 0 arge in t e or nance. UNITED STATES PATENTS When air fills the chamber, insufficient forces will be 5312? transmitted and the device will be safetied. 3,020,871 2/1962 Temple et a1. 89/1 B 3 Claims, 1 Drawing Figure BACKGROUND OF THE INVENTION This invention relates generally to arm-safe ordnance devices, and more particularly, to an improvement to a water-armed, air-safe detonator fuze for grenades or the like. A safety problem exists in the use of hand grenades when they are intended to be thrown from boats into the water because they may be accidently dropped into the boat after the safety cotter pin has been pulled. Accidents have occurred, particularly during night operations, when it is more likely to drop a hand grenade in the boat and not be able to retrieve it in time to toss it overboard.

The presently used hand grenades are detonated by first pulling out a cotter pin which retains the hand-held release mechanism for handling and shipping safety. When the grenade is thrown, the hand-held release mechanism separates from the grenade, permitting a spring-loaded firing pin to strike a percussion primer which initiates a pyrotechnic delay fuze coupled to the burster charge. The time delay to the detonation of the burster charge is sufficient to provide adequate separation between the thrower and the detonation. But the conventional hand grenade has been found unsafe for use from boats in water operations. An adapter, to preclude operations of the grenade except when immersed in water, is therefore desired. A patent application Ser. No. 238,600, filed on Mar. 27, 1972, embodying such an invention, has been filed in the U. S. Patent Office. The instant invention represents an improvement to the referenced patent application and includes a drive piston to obtain better discrimination between operation in water and in air.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an improvement in water-armed ordnance fuzes.

Another object of the instant invention is to provide an ordnance that is armed in water and safe in air.

A further object of the present invention is to provide a fuze train having a hiatus when in air and a water piston coupling when submerged in water.

A still further object of the instant invention is to provide a fuze that better discriminates between a water and an air environment.

Briefly, these and other objects of the present invention are attained by the use of an explosively driven piston which acts on the water in a floodable chamber and thence a frangible firing pin and percussion primer of a hand grenade. The explosively driven piston is propelled by a charge which is ignited by the conventional delay train and percussion primer. When the chamber is flooded the water transmits the force developed in the explosively driven piston to a firing pin that is driven against a percussion primer within the adapter. Essentially, the water in the flooded chamber acts like a water piston in front of the explosively driven piston and transmits sufficient energy to fire a percussion primer. When air fills the chamber, because of its compressability and less density, it will not transmit sufficient energy from the driver piston to tire the percussion primer. This embodiment using an explosively driven piston represents an improvement in the discrimination between air and water operations, and provides more reliability for water operation than the referenced patent application because it separates the expanding gases produced by the transfer charge from the water, thus eliminating boiling and vaporization and dispersal of the water in the floodable chamber.

BRIEF DESCRIPTION OF THE DRAWING A more complete understanding of the invention and many of the attendant advantages thereto will be readily understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

The FIGURE is a side view partially cut away of the improved water armed grenade.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, there is shown in the Figure a hand grenade 10 attached to a fuze 12 by a water-arming adapter 14 according to the invention. When conventionally used on land, the adapter 14 is eliminated and the hand grenade fuze 12 is threaded directly into grenade 10.

The hand grenade fuze 12 comprises a conventional hand-held release mechanism and retaining cotter pin (both not shown) which when released, ignite a delay charge 16 contained within a bore having a stepped outside diameter cylinder 18, threadably engaged within adapter 14 which is substantially cylindrical in shape. Over the distal end of the cylinder 18 is a cup 20 crimp-sealed to the cylinder and containing a transfer initiator charge 22 separated from the delay charge 16 by a bore 24 and a washer or disc 26.

Forward of the end of cup 20 is a bore 28 containing an explosively driven piston 27. The bore 28 is connected to a floodable chamber 30 having a plurality of flooding holes 32 connecting the flooding chamber to the outside environment.

Coaxial with the bore 28 holding the explosively driven piston 27 and also communicating with the floodable chamber 30 is a hole 34. Residing in the hole 34 and held secure by an insert 37 is a firing pin 36 having a sharp tip and attached to a shear disc 38. Coaxial with the firing pin 36 and separated by a standoff distance is a percussion primer 40. Displaced from the percussion primer 40 by a conduit 42 is a burster charge 44. The conduit 42 extends within grenade 10 and carries the burster charge 44 which is contained in a cup 48 crimp-sealed to the extension.

In operation, the sequence of events is as follows in the embodiment previously described. The release mechanism (not shown) of the conventional hand grenade fuze 12 is hand-held as a cotter pin and ring are pulled. When the release mechanism is released, as by throwing the grenade, a spring-loaded firing pin (not shown) strikes a percussion primer (not shown, but similar to percussion primer 40) which initiates burning of the delay charge 16. Delay charge 16 eventually burns towards the end adjacent the bore 24 when it produces flashes down the bore 24 to detonate the transfer charge 22. Detonation of the transfer charge 22 produces shock wave energy which acts on the explosively driven piston 27 in the bore 28 to eject it towards the floodable chamber 30.

When the device is immersed in water and the chamber 30 flooded, the explosively driven piston 27 acts on the water with sufficient forces to shear the firing pin 26 from the shear disc 38, ejecting it into the stab percussion 40 detonating it. The flash of the percussion primer 40 detonation initiates the burster charge 44 within the grenade 10.

When the floodable chamber 30 does not contain water as when the grenade is thrown to a land target or it is dropped in a boat, the delay charge 16 and the transfer charge 22 will be initiated, causing the explosively driven piston 27 to be driven forward into the floodable chamber 30, but the other events to subsequently explode the grenade will be stopped at the floodable chamber 30. The air in the chamber will be compressed and dispersed and sufficient forces will not be built up to eject the firing pin 36 and thus preclude the detonation of the percussion primer 40. Thus the device renders the hand grenade safe in air and armed in water.

Obviously, numerous modifications and variations of the instant invention are possible in the light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States Patent Office is:

1. An improvement to a water-armed grenade fuze comprising:

an adapter having a substantially cylindrical body and coaxial bore therethrough adapted to be threadably engaged between a hand grenade fuze mechanism at one end and a grenade at the other end;

a delay charge in said fuze mechanism and initiated by said fuze;

a transfer charge in said bore of said adapter at said one end adjacent to said delay charge;

an explosively driven piston slidably contained in said bore adjacent said transfer charge;

a floodable chamber constituting an intermediate portion of said bore having radial flooding holes communicating with the environment;

a firing pin in said bore adjacent said floodable chamber co-axial with said piston, movable upon receipt of sufficient impulse compression forces produced by the movement of said piston when transmitted by water flooding said floodable chamber, and not movable upon insufficient forces from said piston when transmitted by air filling said floodable chamber;

a percussion primer in said bore at said other end of said adapter, adjacent said firing pin; and

a burster charge at said other end of said adapter, ad-

jacent said percussion primer.

2. The improvement to the water-armed grenade fuze of claim 1 wherein said firing pin is further defined as having:

a flared skirt in sealing relationship with a hole communicating with said percussion primer.

3. The improvement to the water-armed grenade fuze of claim 1 wherein said firing pin is secured by a shearable disc adjacent said floodable chamber.

UNITED STATES PATENT oFEIcE CER'IIFICA'IE OF CORRECTION patent No. 3.165.331 Dated October 16. 1913 w fl Lduis J Montesi It is certified that error appears in the above-identified paterit and that said Letters' Patent are hereby corrected as shownbelow:

r- Change the title of the Invention from the present 3 "Watered-Armed Air Safetied Detonator" to.

-- Water-Armed, Air-Safe Device--.

Signed end sealed this 6th day of August 1974.

(SEAL) Attest: v V

MCCOY M. GIBSON, JR. (3 MARSHALL DANN I Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE 4 CERTIFICATE OF CORRECTION Patent No. 7 5.331 Dated "October 16, 1973' w fl Louis J. Montesi It is certified that error appears in the above-identified pater 1t and that said Letters Patent are hereby corrected as shownbelow:

[- Change the title of the Invention from the present Y "Watered-Armed Air Safetied Detonator" to Water-Armed, Air-Safe Device--.

Signed end sealed this 6th day of August 1974.

c E Li Attest:

McCOY M. GIB'SCN, JR. Attesting Officer I c MARSHALL DANN Commissioner of Patents 

1. An improvement to a water-armed grenade fuze comprising: an adapter having a substantially cylindrical body and coaxial bore therethrough adapted to be threadably engaged between a hand grenade fuze mechanism at one end and a grenade at the other end; a delay charge in said fuze mechanism and initiated by said fuze; a transfer charge in said bore of said adapter at said one end adjacent to said delay charge; an explosively driven piston slidably contained in said bore adjacent said transfer charge; a floodable chamber constituting an intermediate portion of said bore having radial flooding holes communicating with the environment; a firing pin in said bore adjacent said floodable chamber coaxial with said piston, movable upon receipt of sufficient impulse compression forces produced by the movement of said piston when transmitted by water flooding said floodable chamber, and not movable upon insufficient forces from said piston when transmitted by air filling said floodable chamber; a percussion primer in said bore at said other end of said adapter, adjacent said firing pin; and a burster charge at said other end of said adapter, adjacent said percussion primer.
 2. The improvement to the water-armed grenade fuze of claim 1 wherein said firing pin is further defined as having: a flared skirt in sealing relationship with a hole communicating with said percussion primer.
 3. The improvement to the water-armed grenade fuze of claim 1 wherein said firing pin is secured by a shearable disc adjacent said floodable chamber. 